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99 Cavalier 2.2L oil leak behind engine

02-15-2012, 12:44 PM
My 99 Cavalier 2.2L OHV has an oil leak on the backside of the engine, between engine and firewall and below intake. I have replaced the oil pan gasket and oil sending unit. The backside of the crank pulley is not wet with oil so I do not suspect front seal. Oh, and I have also replaced the valve cover gasket. I use about a qt. of oil per two fill ups. (about a qt a week) I cannot tell where the leak is coming from as you can't see anything back there. I will be pulling the head this spring to replace the head gasket and timing chain. Is there something I might look for that could be leaking back there? Any help would be appreciated.

02-19-2012, 11:30 PM
Hey Dexter. I had a 1996 Chevrolet Corsica with the same engine and had the same problem. By any chance is your oil change canister light (not the low oil level) flash when your car idles, or on all the time? If not then double check your oil filter if it's completely sealed. But if that's not the case then read on.

My Corsica did that and it turns out that the oil sending unit went bad. The oil sending unit has been known to malfunction on the 2.2 engines and if it gets stuck open, oil can leak out. It's actually a bit of a pain in the rear end to even access the sending unit, let alone work on it. But it was a 10 dollar part from Auto Zone so it's not expensive. You also need a special oil sending unit socket which is like another 10-15 bucks. It's one of those tools you don't HAVE to have, but it makes removing the old and installing the new 10x easier. But be prepared for a bit of a long time on your back under the car.

This is what caused me to lose about a quart and a half of oil every 3,000 miles. I would usually have to put a quart of oil in about every 1,500 to 2,000 miles because my Low Oil Level light would actually come on because it would get low. The real pain like you said is that its between the firewall and engine

I would definitely research it before you attempt to do it. It took me and my dad about 2 hours together to get it done. I wish I still had the car, I would take pictures for you and help you out. But if you have any questions, I'll try to help the best I can man. Hope this works out for you.

02-27-2012, 07:01 PM
As per my original post... I have replaced the oil sending unit. My Cavalier does not have any other lights on the dash other than the oil pressure light.

Thanks for the reply, though.

02-27-2012, 10:59 PM
you just have to bite the bullet...

clean out that area with some engine degreaser,

get a mirror on a stick tool

and start pinpointing where that leak is going out of:runaround:

agrees that that sending unit is a PITA to get to; i've used a free rental tool in the past from autozone instead of buying one since it's only a rarely used tool...

sometimes the replacement sending unit may be bad as well; it happened to me once with a honda accord (but with that model, it was much easier to get to)

03-07-2012, 06:46 AM
Well I've got the head off and at the machine shop... not sure if it was the head gasket leaking or not, but the crankcase sensor may have been. I'm replacing all of the sensors back there since I can get to all of them now. Don't want to go through this again. The only problem I've got now is the darn thing is plastic and I broke it trying to pull it out... must have a lot of gunk on it. I may have to pull the oil pan to remove it from the inside.:frown:

oh... and the new oil sending unit that I've already put in is not leaking.

03-07-2012, 06:50 AM
Does anyone know what you would call the gasket that goes behind the plate, that the coil pack mounts on, that mounts on the end of the head? The gasket was not included in the head kit that I've got. Guess I wasn't suppose to pull it off.

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